With a system having an interactive processing apparatus in a man-machine interface that uses natural language, the user first inputs data to the system. The system responds to the user's input. In reply to responses from the system, the user makes further entries in an interactive manner, until the user achieves a goal. For the user to interact with such an interactive processing apparatus smoothly and efficiently requires that two situations be suitably controlled: a user-initiated situation in which the user takes the initiative in demanding actions of the system, and a system-initiated situation where the system asks questions of the user to solicit responses and information. The requirement is met by use of a man-machine interface capable of controlling interaction with the user by setting appropriate action goals fit for the user's intentions.
Japanese Patent Laid-Open Publication Number JP-A-63/153631, for example, illustratively discloses an interactive processing apparatus for use with the above-described type of man-machine interface using natural language. FIG. 1 is a function block diagram of the disclosed interactive processing apparatus.
In FIG. 1, the reference numeral 1 is an information providing system such as an information retrieval system that retrieves from storage the kind of information that is just fit for the user's needs; 2 is information output by the information providing system 1; 3 is an input statement in natural language entered by a user; 4 is natural language interpreting means for interpreting the meaning of the input statement 3 in natural language; 5 is command generating means for generating commands to the information providing system 1; 6 is topic managing means for extracting objects attracting the user's attention from the information output by the information providing system 1 in response to the command generated from the command generating means 5, the topic managing means further managing the extracted objects to be referenced during the interpretation by the natural language interpreting means 4; and 7 is object storing means for storing the objects currently attracting the user's attention and managed by the topic managing means 6 as well as a history of such objects.
In the conventional interactive processing apparatus outlined above, commands from the information providing system 1 corresponding to input statements 3 in natural language entered by the user allow the user to interact with the system. Where objects attracting the user's attention are extracted and stored in the object storing means 7, any of these objects may be retrieved and used in context analysis. The feature is intended to facilitate making interpretations in the context and minimize interpretive errors, thus rendering interaction smoother.
What characterizes the conventional interactive processing apparatus above is that it has the information providing system 1 generating the commands corresponding to the input statements 3 in natural language entered by the user and that the apparatus simply carries out the commands thus generated. There are no action goals set for the system, and control is not switched from the user-initiated to the system-initiated interactive situation. This results in the inability of the system to maintain smooth interaction if the information for the system to act on is insufficient or if any input statement 3 from the user contains an error.
Natural language input entails frequent uses of abbreviations and referring expressions. To identify what is abbreviated or referred to requires that the user reenter in more specific and substantive terms what is curtailed or referenced. But an interactive session calling on the user frequently to confirm what has already been input does not really amount to an "interaction" with a tolerable degree of freedom. Hence the need for the system to supplement what is abridged or implied in accordance with the context of interaction. What is noticeable here is that abbreviations or referring expressions do not necessary point to any object attracting the user's attention. The substance of abbreviations or references may or many not appear in the immediately preceding speech. There may exist a plurality of supplementary candidates in the context. Furthermore, there are no fixed rules by which to determine one of any number of supplementary candidates; the rules vary dynamically with the interactive situation. This requires controlling two things: determining whether or not to provide supplementation based on context information, and determining the rules by which to select the contents of the supplement if such a supplement is judged to be necessary.
One disadvantage of the conventional interactive processing apparatus disclosed in Japanese Patent Laid-Open Publication Number JP-A-63/153631 is that because the apparatus deals with only the objects attracting the user's attention, it is incapable of supplementing abbreviated conditions, among others, in information retrieval.
The disadvantage above appears to be circumvented illustratively by an interactive processing apparatus disclosed by Japanese Patent Laid-Open Publication Number JP-A-1/222326. This conventional interactive processing apparatus retains history information about input and output statements employed since the beginning of an interactive session. When the intention of an input statement from the user is interpreted by a given set of rules for interpretation, an abbreviation is supplemented by referring to the history information, whereby the user's intention is determined.
One disadvantage of the conventional interactive processing apparatus described above is that in supplementing abbreviations based on the history of interaction, the apparatus is incapable of dynamically varying the rules for selective supplementation depending on the interactive situation.
It is the therefore an object of the present invention to overcome the above and other deficiencies and disadvantages of the prior art and to provide an interactive processing apparatus capable of setting suitable action goals for a system on the basis of a user's intentions, thereby appropriately controlling the initiative of interaction between the user and the system.
It is another object of the present invention to provide an interactive processing apparatus capable of dynamically controlling rules for selecting context information during interaction on the basis of the interactive situation, thereby contextually processing abbreviations or referring expressions that may appear in input statements in natural language entered by the user.